Mendel’s Peas Unit 18: Genetics Assignment 3: Inheritance Dihybrid Inheritance Mendel’s Peas Unit 18: Genetics Assignment 3: Inheritance
Starter Activity 1 Define the following terms: Allele Heterozygous Homozygous
Starter Activity 2 Bb LL ff Gg Tt WW Ww Which of these genotypes are Heterozygous Homozygous Bb LL ff Gg Tt WW Ww
Starter Activity 3 a) Construct a Punnett square for the following genetic cross: Parent 1: Red Petals Parent 2: Pink Petals Rr X rr b) What proportion of the offspring will have Red petals? Pink Petals
Follow up question: If the plant produced 50 offspring, how many would you expect to have Red petals Pink petals. In nature, do you think this would be the case? What if it produced 10000 offspring, would the outcomes be closer to the expected? Why?
Dihybrid Inheritance The inheritance of two related traits. e.g. The height of a plant and its petal colours T = Tall t = short R = Red r = pink We can write genomes like this: TtRr or TTRR
Punnett Square F1 Generation: Parent 1) TTRR Parent 2) ttrr TR tr
Punnett Square F1 Generation: Parent 1) TTRR Parent 2) ttrr TR tr TtTr TtTr
100 % Offspring have the Genotype: TtRr What is their Phenotype 100 % Offspring have the Genotype: TtRr What is their Phenotype? Tall, Red Construct a Punnett square for the F2 Generation:
Parent 1) TtRr Parent 2) TtRr TR Tr tR tr
Parent 1) TtRr Parent 2) TtRr TR Tr tR tr TTRR TTRr TtRR TtRr TTrr TtRr Ttrr ttRR ttRr Ttrr ttrr
9:3:3:1 ratio Red, Tall = 9 Red, Short = 3 Pink, Tall = 3 Pink, Short = 1
Who Was Gregor Mendel? Pea experiments Inheritance
Class Work Complete the worksheet applying the principles we have covered with tall/short, red/pink flowers to the example of Mendel’s pea plants.
Video: https://www.youtube.com/watch?v=Y1PCwxUDTl8
Plenary Activity: Cats! B = Grey b = ginger S = Dark stripes s = no stripes Write out all possible genotypes / phenotypes:
Answers: You could have: BbSs, BBSS = Grey, Stripes BBss, Bbss = Grey, no Stripes bbSs, bbSS = ginger, stripes bbss = ginger no stripes